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Faulty Low Oil Pressure By-Pass Switch?

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Faulty Low Oil Pressure By-Pass Switch?

Postby Keystone » Sun Mar 05, 2017 10:18 am

Not sure I'm using the right terminology but here it is. My Kohler Aegis EFI has this by-pass switch for start up but it doesn't appear that mine is working. The engine will start up and shut down repeatedly until the oil pressure has built up(I have installed an oil pressure gauge to observe this). It can be very tricky to start especially when it is cold, very easy to flood it out with fuel. Can anyone tell the fix for this problem?
Model LH775S
Spec # LH775-0001
Serial #3610009571
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Re: Faulty Low Oil Pressure By-Pass Switch?

Postby StarTech » Mon Mar 06, 2017 4:07 am

Oil pressure switch is a standard type. Are you getting any error codes?
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Re: Faulty Low Oil Pressure By-Pass Switch?

Postby Keystone » Mon Mar 06, 2017 9:36 am

No error codes. The oil pressure switch has been replaced but made no difference. I don't know exactly how this system works, but as I understand it the by-pass cancels the ignition ground allowing the engine to run for a few seconds even when there is little or no oil pressure. Is this right?
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Re: Faulty Low Oil Pressure By-Pass Switch?

Postby bgsengine » Mon Mar 06, 2017 11:51 am

Using the correct oil filter? Some have an anti-drainback check valve - if the filter is replaced with one that does not have the valve, oil pressure leaks down and takes a much greater time to build up. Also could be sludge sticking a pressure relief valve open?
How poor are they who have not patience. What wound did ever heal, but by degrees? - Iago (Othello Act II, Scene 3)
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Re: Faulty Low Oil Pressure By-Pass Switch?

Postby Keystone » Mon Mar 06, 2017 8:06 pm

I only use Kohler oil filters and it has been doing this for a couple of years. It is my understanding that because my unit has the bypass switch lack of oil pressure on start up isn't suppose to prevent it from running.
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Re: Faulty Low Oil Pressure By-Pass Switch?

Postby Luffydog » Mon Mar 06, 2017 9:43 pm

Check all grounds and ignition wires make sure and is good clean and good ground
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Re: Faulty Low Oil Pressure By-Pass Switch?

Postby Keystone » Tue Mar 07, 2017 9:16 am

Luffydog wrote:Check all grounds and ignition wires make sure and is good clean and good ground

I have looked good at the wiring but will check that further. Wish I had a wiring diagram for this system.
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Re: Faulty Low Oil Pressure By-Pass Switch?

Postby Fulltilt » Tue Mar 07, 2017 9:38 am

Keystone wrote:
Luffydog wrote: Wish I had a wiring diagram for this system.


Been doing it for years, you say ? And yet you don't have a wiring diagram?
Your manual : http://resources.kohler.com/power/kohle ... _07_EN.pdf
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Re: Faulty Low Oil Pressure By-Pass Switch?

Postby Keystone » Tue Mar 07, 2017 11:30 am

Fulltilt wrote:
Keystone wrote:
Luffydog wrote: Wish I had a wiring diagram for this system.


Been doing it for years, you say ? And yet you don't have a wiring diagram?
Your manual : http://resources.kohler.com/power/kohle ... _07_EN.pdf

I have had the service manual since the day I purchased this unit more than 11 years ago and have referred to it many times. I have not found any diagram or description showing the low oil pressure bypass switch. Can you help me with this?
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Re: Faulty Low Oil Pressure By-Pass Switch?

Postby StarTech » Tue Mar 07, 2017 7:08 pm

Don't see anything in the service manual about any other time delay then what is built into the ECU.

Have you tried verifying that the engine start and continue running with the oil sensor disconnected? Just done for testing only.

If does then you may need to add an on delay relay timer. They are fairly expensive but would work fine in you case. They delay the switch over by a specified time on remain active until power is switch off then they reset for the next cycle. This way you would have a delay before the oil sensor come on line while maintaining the shutdown if you should loose oil pressure later during operations.

Now if the system already have delay timer relay then it may maybe adjustable and just need a longer delay.
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